In conventional image coding methods represented by ITU-T standard referred to as H.26x and ISO/IEC standard referred to as MPEG-x, a screen is partitioned into predetermined units, and coded in the partition units. For example, H.264/MPEG-4 AVC (see NPL 1, for example) processes the screen (picture) in horizontal 16 pixels×vertical 16 pixels units which are referred to as macroblocks. For the motion compensation, the macroblock is partitioned into rectangular blocks (horizontal 4 pixels×vertical 4 pixels, minimum), and the motion compensation is performed using a motion vector different for each of the partitioned blocks.